The efficacy of treatment with fotemustine and interferon (IFN) alpha was evaluated in metastatic melanoma. A group of 50 patients with metastatic malignant melanoma were treated with a combination of IFNalpha2b and the nitrosourea fotemustine. The patients received 10 MU IFN three times weekly for 3 weeks and fotemustine at a dose of 100 mg/m2 on days 8, 15 and 22. After a 5-week rest period, patients with stabilized or responding disease received a maintenance therapy consisting of 10 MU IFN three times a week for 1 week followed by administration of fotemustine (100 mg/m2) on day 8. This cycle was repeated every 4 weeks until progression occurred. If there was complete remission (CR), treatment was stopped after an additional three cycles. Toxicity and clinical response were scored according to WHO criteria. Objective response was seen in 14 patients (28%; 95% confidence interval 15.6%-40.4%) with four CR and ten partial responses (PR). The median duration of CR was 73 weeks, that of PR 26 weeks. Toxicity was acceptable, enabling treatment on an outpatient basis. The combination of fotemustine with IFNalpha is effective and well tolerated, but there is no evident advantage over fotemustine monotherapy in the treatment of metastatic melanoma.